When Things Go Too Far They Just Get More Interesting
by sansislife12
Summary: Sans knows it's wrong but he still does it anyway... Just for his pleasure.
1. Chapter 1

"A-ahhh~ B-brother please! This is… s-so… AHH~ Wrong~"

Sans looked up from his positioning to his brother who was biting his hand and blushing way too hard. "What's wrong with it, Papy? Just throwing you a bone, that's all." He chuckled at his little pun.

"SANS! Now isn't a time for your vexatious jokes! I'm seri—agh~" In the time it took Papyrus to get Sans' attention, the latter skeleton had already gotten bored and went back downstairs to the "party." His tongue lapped at the orange liquid that had fallen after the previous "accidental" orgasm.

He pushed Sans' head away, causing him to whine. "What's the matter, Pap?"

"I… I don't think we should continue… It's not right. We're brothers, Sans. Not lovers. I…"

"No. You're right Papyrus. But… I…" He shifted from his spot to meet his brother face to face. His voice dropped to a mere whisper. "I love you… more than just a brother… And when I told you that I loved you, you said you feel the same and when I kissed you, you didn't stop me and I teleported us here and you didn't stop me and—"

"Sans… calm down… It's _okay_ to like me like that, I guess… We can continue if you'd like." Orange magic lightly drifted to the ceiling as he saw his brother nod slowly.

"I'd like that," the older skeleton said as blue magic also drifted out of his left eye socket. He leaned in so that they were only centimetres apart.

"I guess… I guess I love you too…" Papyrus suggested as he clanked his head with Sans' in what was considered a kiss.

Sans let out a small chuckled and smiled brighter. Summoning an ecto-tongue, he pleaded for entrance. He was warmly welcomed by the opposing tongue. Sans deliquesced into Papyrus' mouth as he became a moaning mess.

"Hnnng~ Papy~" Phalanges snaked down Papyrus' ribcage and near his entrance. He brought his hand back up to the ribs to tease them.

"Mmm… Sa-AHHH-nsss…" He couldn't help but feel that it was still wrong.

"Oh, Papy~" Sans moaned as he left upstairs to return to the "party" once again. One kiss after the other he got to the pelvis bone which was bare. "Papy? Is your magic off or something? There's no… there's no, uh… _thing…_ there."

"I'm sorry, Sans. I just… It doesn't feel right anymore. Maybe we should just go back to bed. I'm not really in the mood anymore." Papyrus pulled the blankets back over him, trapping Sans in the process.

Sans grunted and got out from underneath the blankets, sitting promptly on his kneecaps. "Fine," he muttered to his self. He crawled into bed and waited for the sound of Papyrus' snoring.

Quietly, he got out of bed and took the sheets off of Pap's lower half.

"Nyeh… Mettaton~" Papyrus said as he turned onto his side.

"Damn it, Sans, think. Papyrus can't see me doing this… He'll never forgive me… _I'll_ never forgive myself." He looked around the room for a blindfold. His eyes fell upon one of Pap's scarfs. "Perfect."

He looked at Papyrus. He didn't want to wake him up so he used his magic to pick the scarf up, lift Pap's head, tie it, and put it back down peacefully. Papyrus never even stirred.

"Good," he whispered, feeling somewhat proud of what he just did. He conjured up more magic to get another scarf and proceeded to tie up Pap's hands. "I'm sorry for this. I can't have you attacking me."

"Nyeh… M-Mettaton?" He turned onto his back again.

"Thanks, Papy," Sans whispered. He quietly began leaving trails of kisses down Papyrus' spine. His bony hands traced along Pap's ribs.

"Hnnnng~ Mettaton~"

Sans ignored him and continued. A hand traced along the spine and down to the pelvic bone where there was nothing. It rubbed in circles, first small, then larger until his whole hand was groping it.

The hand upstairs slithered down to the inner thigh bones were it went up and down, up and down.

"Ohhh! M-More, Met-Mettaton~"

"I see how it is, Pap. Thinking I'm Mettaton…" He scoffed at the thought but still continued to work at his business.

With both hands now tracing Pap's inner thigh bones, Sans wriggled down the sheets so that he could see Papyrus' pelvic bone himself. There was still nothing there. But that could easily be fixed. He stuck out his tongue, short and flat, and started to trace along it in a circular motion.

"METTATON!" Papyrus jolted up, scaring Sans half to death. "What's going on?"

 _Oh shit. Oh shit. Oh shit. Oh shit. Oh shit. What do I do?_ "Um… Just calm down, dearie. I'll give you a good time…" Sans said in his best Mettaton voice.

Papyrus, not even noticing that there was something wrong with 'Mettaton's' voice just sat there dumbly. "Is the blindfold and hand-tying necessary?"

"Very much, dearie. It makes things more… interesting… to say the least."

"Oh alright. Just be gentle."

 _Finally,_ Sans thought as he saw the orange ecto-vag appear. He removed his hands from the thighs and carefully outlined the clit. It started to throb, begging for more attention. Very lightly, he teased it by going in small circles around it.

"Please~ M-more~" Papyrus begged.

Sans smiled, even though he knew Pap couldn't see him, and began to rub a little faster and a bit harder. Going from there, he only continued to pick up the pace, rubbing faster and faster until finally—

"AAAAHHHHHH!" Papyrus moaned as he came onto the bed, panting heavily and orange cum leaking out at a steady pace. Sans quickly got to work and licked it up. As soon as he was done licking up Papyrus' cum, he started to silently take off his shorts.

"I'm gonna put it in, dearie. Okay?" Sans asked, now in a seductive Mettaton voice.

"P-please…" he whimpered, almost as if he was… lusting…?

 _Whatever you say, Pap._ Sans slowly put his erect blue member in. A bit tight, but otherwise okay. He kept sliding in until it swallowed the whole thing. Slowly pulling out, he thrusted back in, maybe a bit too hard for the other skeleton.

"AHHH!" he screamed/moaned at the same time. Sans scrunched his face.

 _Whoops…_ Nevertheless, he continued in the rhythm of pulling out and going back in. Papyrus just laid there and took it, moaning Mettaton's name instead of Sans'. He could feel his self getting close to climax so he sped up the pace and hoped that Pap was close too. Thrust after thrust, Sans kept getting faster and faster.

"I'm s-so close…" he said quietly, trying not to give it away that he wasn't Mettaton after all.

Faint footsteps could be heard in the hall.

 _What the hell is going on in there?_ She thought to herself as she heard the moaning. She decided to step in. Opening the door, oblivious to what the two skeletons were doing she said: "Papyrus you're late for your… training…" She stared at them, finally realizing what was going on.

Sans gave one more thrust before they both came and finally realized that Undyne was right there.

"Holy shit," Sans whispered as he shook his head and symbolled for her to be quiet.

"What's going on here?" she asked, extremely confused.

"UNDYNE?! Oh no… I'll never get into the Royal Guard now…" Papyrus brought his tied up hands to his skull and cried.

Sans poofed away his ecto-dick and got off of Papyrus. "Sorry, Pap," he said in his normal voice.

"Sans? Undyne? What the _hell_ is going on here?"

Undyne and Sans both looked at each other, shocked that they had just heard Papyrus curse for the first time.

"I…" Sans began, not really sure what to say at that point. "I lied. I'm sorry, Papyrus. I just… I _love_ you."

"Sans," Papyrus began to say. He stopped his self. "I love you too, brother," he finally said.

"You're still late for your training," Undyne mentioned again.

"I'll be there in a minute. Brother, untie me please. We have _a lot_ to talk about once I get back."

Sans obeyed and untied his brother. Looking each other both in the eye socket, Papyrus could see all the sorrow in Sans' sockets. He was deeply and truly sorry for once in his life. Papyrus couldn't be angry at that face…

"Brother. Come closer."

Sans leaned in closer. Papyrus took his gloved hand and put it on the back of Sans' head while he pulled him in for a sweet clank on the teeth. Almost as if on cue, the shorter skeleton summoned an ecto-tongue. The second Papyrus let him enter, he bit the other's tongue, resulting in a scream and a glowing eye of anger.

"What the hell?" he muttered to himself more than Papyrus.

"Don't EVER do that again," he stated as he left the room, passing Undyne's shocked face in the process.

The second Sans tasted magic/blood, he knew things would just get more interesting over the week.


	2. Chapter 2

It had been an agonising afternoon. Sans patiently waiting for Papyrus to return home from training, Papyrus taking his sweet-ass time going to the store to get things, Sans waiting even longer. God, the tension that filled the air was intoxicating. Papyrus had told him that he would have a serious talk with Sans once he got home, but it didn't seem like anyone was going to walk through that door anytime soon.

He just sat there, waiting. The television was off which left the entire house silent. Sweat bullets were already forming on Sans' cranium.

"Come on, Paps. Hurry the hell up..." Sans started to gently bounce his right leg up and down—something that he never did—as he recalled yesterday's foreplay.

Sans using his magic to tie up Papyrus, Undyne walking in on them, Sans confessing, Papyrus screaming out Mettaton's name, Papyrus biting his tongue. Then Papyrus telling him that they were going to have a talk. And if Papyrus biting his tongue didn't already scare him enough, this 'talk' was going to make him cower in fear.

"Brother, I'm home!" Papyrus beamed, closing the door behind him. He carefully placed the grocery bags down.

"P-P-Pa-Pa-Papyrus... I-I-I..."

"Are you alright, brother? You look awfully nervous. Is there something you need to talk about?"

 _What? Had he already forgotten that_ he _was supposed to talk_ me? _No... Papyrus never forgets anything..._ "I-I'm fine, Pap. REALLY! I-I am." He slapped a fake smile on his face in attempt to get his brother to believe more.

"Hmmm." The taller skeleton just shook it off. "Anyhow, we still need to have that talk. I need answers, Sans. Why did you do it?"

The shorter skeleton was at a loss for words. Why _did_ he do it?

"Sans," Papyrus said as he took a seat on the couch next to him. "Tell me, now."

"I'm sorry, Papyrus. I just got so wrapped up in... and I couldn't-I couldn't stop... and I'm just so sorry..." Tears welded at the corners of his eyes, all the sorrow back in his face from the night before.

The younger skeleton shook his head in disbelief. "Are you telling me the truth, Sans?"

"No..." he whispered.

"Why?"

"I just thought that you wouldn't love me anymore if I told you the truth. A-and I want you to love m-me back... I... You... You were just so... I couldn't control myself, Paps. I was... _in heat..._ " Sans lied right through his fake smile.

"Sans, of course I'll always love you... But sometimes in life, you need to learn when to stop." His face brightened up. "Fortunately, Undyne was just talking to me about what they do to people who've been bad! It's sort of like in her anime!"

"But I haven't been bad, Paps... have I?"

"Sans... After what you did to me the other night, I-I can't look at you quite the same anymore. I can't help but to feel like you _are_ a bad guy... So I got some things to 'teach you a lesson' as they would say."

"What kind of lesson, Paps?"

"You'll see..." The lengthy skeleton went over to the grocery bags and pulled out some rope.

"Papyrus... w-what are you doing?"

"Well, part of what Undyne told me was that they handcuffed them. And since the handcuffs were entirely too expensive, I just decided to get rope instead. I hope it'll work, though..."

"P-Paps, I-I-I don't think that's necessary. M-maybe you could just p-put that away?"

"I'm sorry, Sans, but this _must_ be done. I can't have you doing the same thing to me again." He walked over to Sans and reached for his wrist. The older pulled back, shaking his head. "Sans, don't make this more difficult than what it already is. Now just please give me your hand."

"N-no... There's something wrong with you, Papyrus..."

"Ok... so I took a trip to Underfell for some obedience lessons, what's the big deal about it? The other me is part of the Royal Guard already!"

"Underfell?" Sans whispered under his breath. He knew _all_ about that dreaded place. His doppelgänger was a slave to his brother. Calling him 'Boss' and wearing a collar everywhere he went. Hell, the dude was a full-on masochist.

"Oh yes. They even taught me how to do this!" Papyrus brought both his eyes aflame a light apricot orange colour and stuck his hands towards Sans, open-palmed. Then he closed his eyes and clenched his fist, turning Sans' soul blue.

"WHAT THE HELL?"

"Nyeh heh heh, don't worry brother, it's perfectly safe! I promise I'll be gentle." Papyrus brought forth Sans' and tied his wrists together.

"Paps, please! I don't want this! Let me GO!"

"The other Papyrus told me something like this would happen... That's why he told me to ignore it and carry on. That it was perfectly normal and nothing to worry about. But if you really don't want this, maybe I should..." Papyrus' thought drifted off as his eyes fell upon the grocery bags on the floor.

"LET ME GO!" Sans roared. He brought the rope up to his mouth and pried at the knots with all his might, trying to get it off or even loosen it up.

"Please stop making this harder, Sans." Paps placed a chaste kiss upon Sans before gagging him. Despite having tear ducts, the tears flowed down Sans' face and collected at his chin, dripping on his white t-shirt.

"Pheeeeph... Phaaaphhh..." The poor skeleton clawed at the gag helplessly. Papyrus just shook his head and got out the last item—a collar with a leash. Sans shook his head as he brought up his arms for protection.

"Listen, would you, Sans? Please!" Grabbing his wrists, he forcefully yanked them down and gave them a bit of a twist, earning a yelp from the smaller one.

Once he got the collar on, he looked over Sans. Shaking violently, crying, whimpering, waiting, _begging,_ to be released from this hell he was being put through. Papyrus just simply tugged the leash, telling Sans to come along with him.

But he refused to even budge a millimetre.

"Sans... I would highly suggest you move." He all but moved. "Fine. I don't have a choice, then." Papy took his arm and lifted Sans up using his magic. He moved Sans off the couch and put him on the floor.

"On all fours!" he barked. Sans did as he was told and began to crawl towards him. "To the bedroom!"

"Phaph o!" Sans shook his head and he gripped the chain.

"Sans. You will do as I say..." He yanked the chain with all his might, making Sans leap and fall face first into the carpet. "Get up!" Sans struggled but made it up on all fours like he was told to be.

Papyrus tugged on the leash, signalling for the other to walk up the stairs. He followed soundlessly. They both walked into Sans' room, a mess like always.

"Now, clean this abomination!" Papyrus simply stated, standing in the centre of the room and looking around to see exactly how he wanted it. Sans began to pick up one of his socks with his tied hands.

"Not with your hands, do it with your mouth!" Sans looked at Papyrus who walked over and took the gag off. Sans gasped for air, acting like he had just held his breath for six minutes. "Come on! No dillydallying!"

Sans got right to work, picking up all his dirty socks with his mouth and putting them into the hamper in the corner, disassembling the self-sustaining tornado, pushing the treadmill to the side of the room. The whole time he was cleaning, he was trying to think of things to say to Papyrus. Try to make his go easy or just forget about the whole situation in general.

"Now for your bed." Sans looked at Papyrus again.

"W-what about it?" he asked hoarsely.

"I never said to talk!" he snapped, a serious look on his face. Sans just sat there and cried harder but not louder. He hated his life right now. If only he hadn't done that stupid thing in the middle of the night...

"I guess I can just make it..." he shrugged, gathering up his magic and making the bed all neat. For the first time, Sans' room was spotless.

"On the bed, on all fours, and facing the wall!" he ordered as Sans scrambled to follow his command. "Now... if you make _one_ sound... I'll put the gag right back on." Sans silently gulped as he felt his shorts being tugged down.

"Paps..." he whispered, hoping it wasn't loud enough to be heard by Papyrus.

"What did I say?" Apparently he wasn't quiet enough. He returned the gag, feeling some of Sans' tears fall atop his hand. "Enough with your senseless crying, Sans. There's no need for it!"

 _If only you knew..._ Sans thought as he willed his self to stop the waterworks. He could feel his shorts draped on his kneecaps.

"Now, form one of those ecto-dicks." Sans' eyes widened but he did as he was told, conjuring up his magic to create an ecto-penis on his pelvic bone. Papyrus made one of his own, pulling down his pants, and plunging it deep within Sans without a first warning.

Papyrus snaked a hands towards Sans' ecto-dick and slowly stroked it and he rammed into his backside faster and faster. Almost reaching his peek, Sans let out a whiny moan.

"You can't cum until I say so." Papyrus gripped the member hard, sending a wave of pain throughout Sans' body as he was just about to climax. Papyrus continued to ram into him at an inhuman speed until he climaxed, leaving orange strings of cum on Sans' ribcage.

"Pheeeeph," Sans moaned, legs shaking uncontrollably from the denial of cumming.

"Cum." Papyrus loosened up his grip and Sans' seed immediately fled, relieving him. "On your back," Paps said, looking stern. Sans flipped over and flopped onto his back, not caring that the cum seeped onto his bones.

"Now take this like a good boy." He took off the gag once again and got on top of Sans' face, putting his ecto-dick into his mouth. He went in more and more until the skeleton beneath him was deep-throating it. He gripped the collar and brought Sans' face even further up, if it was even possible at this point.

"Good..." he moaned as he began to thrust in and out. Picking up the pace, he told Sans not to cum again. "If you do... y-you'll be a b-bad boy..." Sans made an ecto-tongue and swirled it around Papyrus' length, causing him to moan more. Once again, he climaxed, Sans swallowing every last drop of it.

"Nyeh... You've been a good boy, Sans. You haven't cummed already, have you?" He shook his head. "Good boy. Now you can get your treat." Papyrus took Sans' member and began to stroke fast, knowing the other was already so close. Only a few seconds later, did he come onto his brother's gloved hand, causing him to shiver form head to toe.

"Have you learned a lesson yet, Sans?"

"Mmhmm..." he hummed as he nodded.

"Good. You may speak now."

"I love you!" Sans blurted out.

"Nyeh, I love you, too, brother." The leash was given a playful tug as the two skeletons conjoined for another kiss. Papyrus summoned an ecto-tongue and traced Sans' bottom teeth. Their tongues collided; it was their first passionate kiss they ever shared. That was until, Papyrus bit Sans' tongue again.

"What the hell? Again?" Sans drew back, giving Papyrus a mean glance.

"Maybe that'll teach you to be quiet when it has been requested upon," is all he said before he got up and left the room.

The same magic/blood taste filled Sans' mouth once again, leaving him to think that things could only get worse throughout the week.

Author's Note:

Yes, I know the ending is almost the same... DEAL WITH IT!

Anyhow, here's your smutty sequel you wanted you dirty fontcest sinners.


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